1. Field of the Invention
The present invention relates to an image pickup system in which an image pickup unit is connected for use to an external apparatus arranged to process images.
2. Description of the Related Art
Computers having connection terminals of the PCMCIA standards are generally arranged to be usable with card-shaped units of various functions inserted therein as a facsimile, a memory, etc. The connection terminal permits use of each of the various card-shaped units by replacing one with another so long as they meet the PCMCIA standards. The connection terminal thus permits selective use of card-shaped units of various functions as desired by the operator.
FIG. 7 shows by way of example an image pickup system which is composed of a computer having the above-stated connection terminal and an image pickup unit which is removably attachable to the computer.
The illustration of FIG. 7 includes a card-shaped image pickup unit 21, computers 22, 24 and 26 which are usable in the image pickup system, and connection terminals 23, 25 and 27 which are respectively arranged to connect the image pickup unit 21 to the computers 22, 24 and 26. A case where the image pickup system is formed by connecting the image pickup unit 21 to the connection terminal 23 is first described as follows.
Referring to FIG. 7, an image is picked up by an optical system and a CCD which are included in the image pickup unit 21. The image picked up is converted into digital image data. The picked-up image data thus obtained is transferred through the connection terminal 23 to the computer 22 at a predetermined speed.
The image pickup unit 21 sends the picked-up image data which includes a color signal to the computer 22 at a rate of n frames per sec. The computer 22 then processes the n-frames/sec picked-up image data sent from the image pickup unit 21 and is capable of displaying the picked-up image data on a built-in color display device or recording the picked-up image data in a built-in recording device.
The use of the computer 22 may be replaced with the use of the computer 24. The computer 24 is provided with the connection terminal 25 which conforms to the same standards as the connection terminal 23 of the computer 22 and a color display device which is similar to that of the computer 22.
Since the connection terminal 25 is of the same specifications as the connection terminal 23, the image pickup unit 21 can be connected to the connection terminal 25. With the image pickup unit 21 connected to the connection terminal 25, the computer 24 displays and records the picked-up image data obtained from the image pickup unit 21 in the same manner as when the image pickup unit 21 is connected to the computer 22.
The operator of the image pickup system can use either the computer 22 or the computer 24 and also can use the image pickup unit 21 in common with them.
This arrangement of the image pickup system, however, has presented the following problems.
In the image pickup system shown in FIG. 7, a case where the computer 26 is used will be considered. The computer 26 has a less amount of consumption of electric power and less weight than the computers 22 and 24, but has a slower processing speed than the computers 22 and 24 and has only a monochrome display device instead of a color display device.
Since the connection terminal 27 also conforms with the same standards as the connection terminals 23 and 25, the computer 26 is capable of exchanging data with the image pickup unit 21 as connected to the connection terminal 27. However, since the processing speed of the computer 26 is too slow, it is impossible to completely process the picked-up image data being sent from the image pickup unit 21. As a result, the picked-up image data tends to be lost in part or an image pickup operation sometimes comes to a stop.
Besides, in such a case, it is impossible to utilize color information included in the picked-up image data sent from the image pickup unit 21 as the computer 26 is provided with only a monochrome display device.